1. Field of the Invention
The present invention relates, in general, to a novel optical fiber having a diffuser portion and continuous unitarily-constructed outer sleeve, which is adapted for the transmission of light to a treatment locale. More particularly, the invention relates to a medical instrument with an optical fiber including a diffuser portion at a distal end wherein an alignment sleeve for the optical fiber extends uninterruptedly in a single piece from a connector for a laser light source to at least the distal end of the core of the optical fiber.
Currently, surgeons frequently employ medical instruments which incorporate laser technology in the treatment of benign prostatic hyperplasia, or as commonly referred to as BPH. BPH is a condition of an enlarged prostate gland, in which the gland having BPH typically increases in size to between about two to four times from normal. The lasers which are employed by the surgeons to treat this condition must have durable optical fibers that distribute light radially in a predictable and controlled manner, and must also be capable of bending without breaking, whereby small-sized or slender optical fibers offer an additional advantage to the surgeon.
An optical fiber which is adapted to be employed for this purpose typically contains a glass core surrounded by cladding, a buffer layer, and an outer alignment sleeve. The cladding protects the inherently weaker glass core by imparting a mechanical support to the core. The cladding also ordinarily possesses an index of refraction which is lower than that of the core in order to block light transmitted through the optical fiber from emerging radially from the core. Although optical fibers which are utilizable for such surgical procedures and treatments are widely known and successfully employed, the present invention is designed to provide further significant improvements and advantages over the state-of-the art.
2. Discussion of the Prior Art
An optical fiber with a diffuser portion for diffusing light emitted at an end thereof is disclosed in Esch U.S. Pat. No. 5,754,717 as shown in FIG. 1 of this application, which patent is commonly assigned to the present assignee, and the disclosure of which is incorporated herein by reference. There is illustrated an optical fiber leading end 10 having a diffuser portion 12 comprised of the stripped core of a typical optical laser, an optical coupling layer, and an outer or alignment sleeve 14. The optical coupling layer, replacing a part of the cladding and the buffer layer of the optical fiber, has an index of refraction exceeding that of the core so as to draw the light out of the core using well-known physical principles. The alignment sleeve is abraded, or roughened, in order to conduct light from the optical coupling layer to the exterior, while heat staking or ultrasonic welding is used to apply or attach the portion of 14a of the outer sleeve 14 covering the diffuser tip to a further separate portion 14b of the sleeve located towards the end of the optical fiber.
In essence, the method of forming the diffusion portion of the optical fiber illustrated in FIG. 1 representing the Esch patent, necessitates the presence of a weld joint 16 near the distal end of the remaining cladding. Producers of optical fibers with diffuser portions intended for this or similar surgical purposes are required to ensure an adequate mechanical strength of the fiber for the intended application, and in which the weld joint can result in a stress concentration reducing the strength of the optical fiber. It is also possible that silicone or adhesive from the optical coupling layer may contaminate the area of the sleeve junction during assembly, thereby weakening the weld joint. While the weld joint is deemed to be of adequate strength for most surgical applications, designers would like to use smaller-sized optical fibers. As the diameter of optical fibers become smaller, the degradation in strength of the optical fiber caused by the presence of the weld joint becomes more pronounced and resultingly important. The smaller diffusers can readily break or become detached at the weld joint; whereas the weld seam at the weld joint can catch on instruments and interfere with the medical procedure, thereby creating a nuisance, if not an operating danger for the surgeon.
Other publications which disclose various constructions and types of optical fiber arguments which may be applicable to surgical procedures and treatments employing laser illumination are widely known in the technology.
Anderson et al. U.S. Pat. No. 5,814,041 pertains to an optical radiator and laser fiber in which the distal or leading end sleeve portion of the optical fiber is attached to a second sleeve portion so as to form a weld or contact seam therebetween.
Evans et al. U.S. Pat. No. 5,802,229 discloses a fiber optic radiation system which, similar to Esch, does not provide for a continuous, unitarily constructed outer sleeve for the optic fiber.
Bruce U.S. Pat. No. 5,534,000 discloses a laser fiber apparatus wherein the leading or ablation end of an optic fiber is provided with a relatively short outer tube element so as form an essentially non-continuous sleeve surface providing a seam-like joint or step.
Similarly, Doiron et al. U.S. Pat. Nos. 5,269,777 and 5,196,005; and McCaughan, Jr. U.S. Pat. Nos. 4,693,556 and 4,660,925, disclose various types of optical fibers with light diffusers or similar structures; however, none of which evidence the continuous single-piece outer sleeve of seamless length as provided for by the present invention, nor the method of forming thereof.